Almost every electronic system needs a precise reference value generator to set the operating conditions and to meet the precision needs. Such a reference generator may provide a stable and precise reference value independent of the operating conditions, like supply voltage, temperature and time. Because modern electronic systems are converging to very low supply voltage levels, the reference generator also has to deal with this requirement.
Today, one reference generator most often used in integrated circuits is the so-called bandgap reference voltage generator. As may be known, such bandgap reference voltage generator provides a reference voltage with a very low temperature coefficient balanced within the operating temperature range. The bandgap reference voltage generator may generate a very precise absolute value inside the chip by using imprecise and strongly temperature dependent components.
As the electronic system tends to work at very low supply voltage levels close to the technology limits, the information about the supply voltage status becomes relatively very important. A reliable and stable supply may be one of the most important prerequisites for the reliable operation. Particularly, a significant role may be played by the steady state, and also by the supply start-up and shutdown waveforms.
To allow the integrated device to deal with various supply levels and transitions, it may be good practice to lock its operation until the supply is not at sufficient level. This may be achieved by an under voltage lockout (UVLO) logic signal generation circuit that senses the supply voltage levels and gives logical information to the system.
This measure may reduce some unneeded and often unpredictable effects, like oscillations, overshooting, peaking in analog circuits, and digital information loss in digital circuits.
Different approaches addressing the reference voltage generation and UVLO function exist. As indicated above, a majority of the reference voltage generators is typically based on the bandgap principle. An integrated electronic device of the prior art comprising an under voltage lockout signal generator circuit is disclosed in U.S. Pat. No. 6,600,639. Such an integrated electronic device of the prior art has the drawbacks of increasing of the chip area because the need of a two bandgap core, a first bandgap core to be used in the reference voltage generator circuit, and a second bandgap core to be used in the under voltage lockout signal generator circuit, usually present on the same chip.